Production of magnesium by electrolysis.



UNITED, STATES PATENT OFFICE.

GEORGE O. SEWARD AND FRANZ VCN KI IGELGEN, OF HOLCOMBS ROCK, VIRGINIA,ASSIGNORS TO VIRGINIA LABORATORY COMPANY, OF NEW YORK, N. Y., ACORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Oct. 13, 1908.

Application filed October 10, 1905. Serial No. 282,113.

To all whom it may concern:

Be it known that we, GEORGE O. SEWARD, a citizen of the United States,and FRANZ VON Ki'IGELG-EN, a subject of the German Emperor, bothresiding at ,Holcombs Rock, in the county'of Bedford and State ofVirginia, have jointly invented certain new and useful Improvements inthe Production of Magnesium by Electrolysis, of which the following is aspecification.

When the attempt is made to produce magnesium by electrolyzing a mixtureof magnesium fluorid and an alkali chlorid, it is always found that theseparated magnesium contains injurious quantities of the alkali metal.

tion is as follows :The alkali chlorid, having a lower decompositionvoltage than MgF,, is separated first. The MgF is then reduced by thenascent alkali metal in a secondary reaction. This reaction is, however,not complete, and a portion of the alkali metal alloys with themagnesium.

According to the present invention the above difficulties are avoided byusing, instead of the alkali chlorid, an earth alkali chlorid of a moreelectropositive metal than magnesium (in which term we include one ormore such chlorids), which is decomposed electrolytically only withdifficulty. A pure magnesium is then obtained. For example, MgF andCaCl, are mixed and melted, and then heated until all water is drivenout. The addition of a small percentage of an alkali fluorid as a fluxassists in this operation. The resulting molten mixture is electrolyzed,and'we obtain magnesium at the cathode and chlorin at the anode, theCaCl having been changed to the fluorid.

When the electrolyte becomes too poor in n'iagnesium, it is worked overas follows It is mixed with fused hydrated MgCl. and heated until allwater is driven out. The magnesium chlorid and calcium fluorid(MgCl,+CaF,) change to magnesium fluorid and calcium chlorid (MgF;,+CaClThough we have described with great particularity of detail certainspecific processes Even with a high concentra-' tion of MgF this is thecase. The explanacmbodying the invention, yet it is not to be understoodtherefrom that the invention is limited to the specific embodimentsdescribed.

Various modifications may be made by those skilled in the art withoutdeparture from the invention.

What We claim is 1. The process of producing magnesium, which consistsin fusing together magnesium-fluorid and calcium chlorid, with a flux ofan alkali fluorid, heating to render the bath anhydrous, thenelectrolyzing to produce magnesium, the calcium chlorid being changed tocalcium fluorid, and reconstituting the bath by adding hydratedmagnesium chlorid and heating to dehydrate it, whereby the calciumfluorid and magnesium chlorid react to form magnesium fluorid andcalcium chlorid, and resuming the electrolysis.

2. The process of producing magnesium, which consists in electrolyzing afused mixture of magnesium fluorid and a chlorid of an earth-alkalimetal more electro-positive than magnesium. 7

3. The process of producing magnesium, which consists in electrolyzing afused mixture of magnesium fluorid and a chlorid of an earth-alkalimetal more electro-positivc than magnesium, and renewing the magnesiumcontent of the electrolyte by the addition of a magnesium salt.

4. The process of producing magnesium, which consists in electrolyzing afused mixture of magnesium fluorid and a chlorid of an earth-alkalimetal more electro-positive than magnesium, with a small percentage ofan alkali fluorid as a flux.

5. The process of producing magnesium, which consists in electrolyzing afused mix ture of magnesium fluorid and an earth-alkali-chlorid ofa moreelectro-positive metal than magnesium, and renewing the magnesiumcontent of the electrolyte by addition of magnesium chlorid, whichreacts with the earth-allmli fluorid produced by the electrolysis, toform magnesium fluorid.

6. The process of producing magnesium, which consists in electrolyzing afused mixture of magnesium fluorid and a chlorid of an earth-alkalimetal more electro-positive than magnesium, and renewing the magnesiumcontent of the electrolyte by addition of fused hydrated magnesiumchlorid, heating to expel the water, again to electrolysis.

In witness whereof, we have hereunto and subjecting it signed our namesin thepresence of two subscribing witnesses.

GEORGE O. SEWARD. FRANZ VON KUGELGEN. lVitnesses:

DOMINGO A. UsINA, THEODORE T. SNELL.

